1. Field of the Invention
The present invention relates to a separation membrane module suitable for the field of treatment of water, such as waste water, sewage water, drinking water, etc., and more particularly, to a submerged hollow fiber membrane module which is easy to expand the processing capability of the module according to a processing capacity, suitable for the treatment of a large amount of water because the installation area is small, capable of preventing foulants by an effective air diffusion.
A polymer separation membrane is being distributed to a wide variety of fields including the field of existing applications along with the development of its technology, especially, its demand is being increased in the field of water treatment along with the importance of the environment. A hollow fiber type membrane is generally such a module whose membrane is protected by a cylindrical case since it has an advantage in water treatment because of its high throughout per installation area while its mechanical strength is low due to the characteristics of a porous membrane structure. In the module of such type, in case of waste water treatment, as generally known, it is hard to remove foulants accumulated on surfaces of a membrane, and the permeability is lowered due to fouling.
2. Description of the Related Art
In order to solve such a problem, submerged modules with no case had been devised. However, in a case that the strength of a membrane is not high enough, there may bring out the degradation of system reliability due to membrane damage. In this case, if air diffusion is not efficiently achieved, a fouling problem still occurs to thus increase the operation pressure and lower the flux.
In order to minimize the loss of permeability of the submerged module, foulants accumulated on membranes have to be removed by air diffusion. At this time, a strong air diffusion condition is required, thus there is a possibility that hollow fiber membranes are damaged.
Korean Registered Patent No. 22807 proposes a module fixed by developing a hollow fiber membrane in a conical form and folding it in a U shape in order to prevent the pollution of the membrane under a mild air diffusion condition. In this case, however, the volume of the module becomes larger and it is not easy to couple between modules for increasing a processing capacity from a structural viewpoint.
A submerged module disclosed in Korean Registered Patent No. 236921 is characterized in that a hollow fiber membrane is not fold in a U shape but air injection port and a filtrate water outlet are connected to one portion of the module with both ends of the hollow fiber membrane being fixed in a I shape. Such module structure is inefficient to the arrangement of a water collecting pipe and an air injecting pipe in coupling a plurality of modules for increasing a processing capacity, and the filtrate water outlet and the air injection port coexist on one portion of the module, to thus decrease workability in the manufacture of a module.
Especially, in case of a module used for the treatment of a large amount of water, a rectangular shape in which a bundle of hollow fiber membranes is widely spread is more convenient for collecting a number of modules in a small installation area than a cylindrical shape. The module of such a shape has a merit that it is capable of producing a large amount of treated water on a small installation area, while there is a big possibility that foulants would be accumulated because a bundle of hollow fiber membranes are densely concentrated, thus an efficient air diffusion process has to be accompanied. In this procedure, due to a direct impact applied to membranes, there may be occurred the degradation of quality of treated water by the damage of membranes and a water leakage caused by the loosening of joint portions between module parts when the membranes are used for a long time. Further, in a case that a number of modules are coupled according to a treatment capacity when adapted to a large-scale water treatment, an efficient arrangement is impossible and thus it is difficult to minimize the installation area and it is not easy to couple them.